One of the most exciting advances in cardiac life-saving techniques is bringing back patients who have experienced cold water drowning and severe hypothermia — hours after the person was submerged.

"A life could be saved right here on the Seacoast this winter if someone has this knowledge," said Dr. Robert Helm, a cardiac surgeon at Portsmouth Regional Hospital.

While all emergency medical services personnel have been trained in cold water drowning rescue, the average person can save a life by doing chest compressions and calling 9-1-1.

"The most important thing is not to try to warm the person," Helm said. "All the EMTs know that they should never give up."

Once the patient arrives by ambulance at the hospital, he or she is immediately put on a cardiopulmonary bypass machine to restore blood flow, and then slowly warmed.

Helm gave a case study of a 3-year-old girl who fell into a fish pond with a temperature of 46.4 degrees Fahrenheit. She was found 30 minutes later by her parents who began CPR under direction of the operator on a 9-1-1 call. The emergency team arrived eight minutes later and the child was asystolic (without a heartbeat) and comatose, with dilated pupils and a core body temperature of 65.66 degrees Fahrenheit. Emergency medical personnel continued CPR and the girl was transported by helicopter to the nearest hospital with a cardiac team who could treat her. This took 25 minutes.

The girl was put on bypass and gradually warmed over three hours. When her temperature reached 75.2 degrees Fahrenheit, there was spontaneous cardiac rhythm. She was extubated 12 days later and had normal neurological function, meaning no evidence of brain damage. She was reassessed 20 months later and there were no adverse consequences to the accident.

In another case, a 32-year-old physician fell through a river ice sheet as she was cross-country skiing. She was trapped underneath the ice and pulled downstream as her friends helplessly watched.

Her body was recovered 79 minutes later through a hole cut in the ice. She was pronounced dead at the scene, but a physician friend initiated CPR. The CPR was continued during an air ambulance flight to the hospital while the patient's core body temperature was kept at 56.66 degrees Fahrenheit.

The patient was on ventilator support for 35 days and five months later returned to work as a hospital physician.

"A lot of people just don't realize that a person can be underwater for even two hours and still be resuscitated," Helm said.